DESCRIPTION: (Adapted from applicant's description) Dr. Crawford's laboratory has recently identified a number of genes that are induced by oxidative and other stress in hamster HA-1 cells using the method of differential display. When one of these, named adapt78, was cloned and sequenced, it was found to be homologous to a recently reported gene, DSCR1, located in the obligate region of HSA21 where genes associated with Down syndrome, Alzheimer's disease, and other neural disorders are localized. In addition, higher expression of adapt78/DSCR1 mRNA was found in both brain and heart and may be related developmentally to mental retardation and congenital heart disease that are major clinical features of patients with Down syndrome. Thus, adapt78 represents a gene whose overexpression in Down syndrome may produce specific pathogenetic effects due to gene dosage in the trisomic condition. Dr. Crawford proposes specific studies in this RO3 application to determine whether adapt78 plays a role in the etiology of Down syndrome and other stress-related disorders. He proposes to have the NICHD-supported transgenic mouse facility at Alabama generate mice that express human adapt78, following microinjection of a cDNA of human adapt78 under the control of the CMV promoter. Mice identified as positive by PCR will then be studied to determine whether they express adapt78 mRNA, to what level, and in what tissues.